The invention relates to a pushbutton tuner, and more particularly, to a dual band pushbutton tuner having a pair of tuning slide members which can be selectively actuated by a pushbutton slide.
In dual band pushbutton tuners of known form, each pushbutton slide is engageable with a selected one of a pair of tuning slide members disposed on the opposite side thereof and disengageable from the other tuning slide member by means of a shuttle or shuttles which move together with a manually operated shift member. In U.S. Pat. No. Re. 27,179 and U.S. Pat. No. 3,415,129, the shuttle comprises a toggle lever mounted on the pushbutton slide and alternately tilts or oscillates from one of the tuning slide members to the other. In order to hold the lever at a definite operative position, a snap action or over-center effect is produced between the lever and the pushbutton slide. In U.S. Pat. No. 3,463,017, the shuttle comprises a rigid horizontal bar which is slidably carried within a groove formed in the pushbutton slide for alternate axial movement across the pushbutton slide from one of the tuning slide members to the other. U.S. Pat. No. 3,646,821 and German Laid-Open Patent Application No. 2,522,273 disclose a shuttle comprising a flat plate which is pivotally mounted on the pushbutton slide. The plate is adapted to rock on the pushbutton slide between the pair of tunning slide members. German Laid-Open Patent Application No. 2,522,274 discloses a pair of shuttles carried by the pair of tuning slide members through spring materials, and a selected one of the shuttles is engageable with the pushbutton slide by undergoing an elastic movement.
With these shuttles of various forms as mentioned above, they are moved by the shift member between one of their operative positions and the other or between their inoperative and operative positions when switching a tuning slide member which is to engage the pushbutton slide. A usual pushbutton tuner includes as many as five or ten shuttles associated with five pushbutton slides, for example, so that this increased number of shuttles must be simultaneously moved by the shift member, requiring an increased force to operate the shift member. It will be apparent that the force requirement will be even greater when each shuttle has a snap action or over-center effect. With pushbutton tuners of the type in which the respective shuttles slide along the surface or grooves formed in the pushbutton slides, the resulting friction also requires an increased force to operate the shift member.